1. Field of the Invention
The invention generally relates to a class of salicylic acid esters and, more specifically, the invention relates to a class of diol-disalicylates useful as waxes, including cosmetic waxes, as ultraviolet radiation absorbers, and in the treatment of skin conditions including acne.
2. Brief Description of Related Technology
Cosmetic compositions generally are defined as compositions suitable for application to the human body. Cosmetic compositions such as creams and lotions are used to provide moisture to hair and skin and to keep skin in a smooth, supple condition. Pigmented cosmetic compositions such as makeup, blush, lipstick, and eyeshadow are used to color the skin and lips.
In general, cosmetic emulsions are composed of a fatty phase, an aqueous phase, active materials and, optionally, pigments, preservatives, and ultraviolet radiation filters. Cosmetic compositions can also be anhydrous systems containing waxes, oils, and pigments. In the fatty phase, in addition to emulsifiers, oil components and antioxidants, consistency regulators are employed to increase the viscosity and thus to improve the consistency required for a stable emulsion system. Consistency regulators in water-in-oil emulsions include, for example, beeswax, paraffin, petroleum jelly, microcrystalline waxes, and metal stearates. In oil-in-water emulsions, it is customary to use spermaceti, fatty alcohols, and glycerofatty acid esters.
Waxes are lower-melting organic mixtures or compounds of high molecular weight, solid at room temperature, and generally are similar in composition to fats and oils except that they contain no glycerides. They can be hydrocarbons or esters of fatty acids and alcohols. Waxes generally can be categorized as animal waxes, vegetable waxes, mineral waxes, natural waxes, synthetic waxes, petroleum waxes, ethylenic polymers, hydrocarbons such as Fischer-Tropsch waxes, silicone waxes, and mixtures thereof
Natural waxes traditionally used in cosmetic compositions include waxes of animal origin, e.g., beeswax, spermaceti, and lanolin (wool wax); waxes of vegetable origin, e.g. candelilla, carnauba, bayberry, and sugarcane wax; waxes of mineral origin, e.g. ceresin, montan, and ozokerite; and waxes of petroleum origin, e.g. paraffin and microcrystalline wax. Animal, plant, and some mineral waxes are primarily esters of a high molecular weight fatty alcohol with a high molecular weight fatty acid.
Synthetic waxes include long chained polymers of ethylene oxide combined with a dihydric alcohol, namely polyoxyethylene glycol, (including carbowax), hydrocarbon waxes derived from carbon monoxide and hydrogen (Fischer-Tropsch synthesis waxes), and silicone waxes such as methyloctadecane-oxypolysiloxane and poly(dimethylsiloxy)stearoxysiloxane.
Cosmetic waxes have an emollient effect on the skin, giving a film permeable for moisture (i.e. water vapor) and gas. Cosmetic waxes have, and impart, desired characteristics to a cosmetic composition such as structure, body, or hardness (e.g. in lipid-based materials such as lipsticks and hair pomades), high viscosity (e.g. to emulsions and suspensions), spreadability, long wear, and stability. Typically, cosmetic waxes will have a melting point in the range of about 32xc2x0 C. to about 120xc2x0 C.
Candelilla, a typical cosmetic wax, has a melting point of about 70xc2x0 C. Most waxes having a melting point of about 70xc2x0 C. provide structure and hardness, but have a waxy, tacky, or grabby feel. Cosmetic compositions made with traditional cosmetic waxes may be prone to oil breakthrough, creasing, ruboff, and difficulty adhering to pigments. In addition, some natural waxes, such as beeswax, are in increasingly short supply. Synthetic waxes, although useful in some cosmetic applications, can also have undesirable tactile or compositional characteristics and also may be costly to produce.
Beta-hydroxy acids (BHA""s) also have been used in cosmetic compositions. BHA""s include salicylic and citric acids, derivatives of salicylic acid, and their salts. BHA""s are lipid soluble and penetrate to the thicker dermal skin layers located below the epidermis. BHA""s are effective in exfoliating the lower dermal skin layers, which results in increased cell turnover and the production of new skin cells. It is known that salicylic acid esters and salicylic acid derivative esters, such as tridecyl salicylate, are broken down by esterases in human skin, releasing salicylic acid. It is also known that salicylic acid derivatives and their esters are effective in controlling, reducing and inhibiting oil and grease production by skin. Thus, BHA""s are useful in the treatment of adult acne, reversing the effects of premature skin aging, reducing thin lines and wrinkles, and producing firmer, smoother-looking skin.
PCT applications WO 93/10755 and WO 93/10756 report salicylic acid as an effective anti-wrinkling agent. U.S. Pat. No. 5,262,407 reports use of ring acylated salicylic acid as a treatment against skin aging. Salicylic acid has also been described for the treatment of acne in U.S. Pat. Nos. 4,891,227 and 4,891,228. Moreover, salicylic acid has been used for the removal of warts, corns, and calluses; for the treatment of psoriasis, seborrheic dermatitis, and dandruff; and for the topical treatment of ringworm infection.
Sunscreen agents also have been used in cosmetic compositions. Lengthy exposure of the skin to ultraviolet (UV) light typically damages the skin, resulting in sunburn, photoaging, and carcinogeneses. The results of photodamage may be identical to those of aging except that they appear at an accelerated rate. Wriniding, yellowing, leatheriness, mottling, and hyperpigmentation are also associated with sun damage. UV light exposure in the presence of oxygen results in the creation of free radicals. In the skin, these radicals frequently trigger the release of inflammatory mediators, commonly manifested as sun burn, cytoskeletal alterations, breakdown of collagen in the skin, and may also result in structural DNA changes, such as DNA strand breaks and dimer formation.
Sunscreen agents and sunscreen formulations for use on human skin are widely used and are available for diverse consumer needs. Different agents and formulations give different Sun Protection Factor (SPF) values, from 2-4 (xe2x80x9cminimalxe2x80x9d protection), 4-6 (xe2x80x9cmoderatexe2x80x9d protection), 8-15 (xe2x80x9cmaximumxe2x80x9d protection), and above 15 to indicate xe2x80x9cultraxe2x80x9d sun protection.
Sunscreen components include dioxybenzone (benzophenone-8), ethylhexyl p-methoxycinnamate (octyl methoxycinnamate), 2-ethylhexyl salicylate (octyl salicylate), oxybenzone (benzophenone-3), titanium dioxide, p-aminobenzoic acid (PABA) and PABA derivatives. Various other sunscreen materials are found in xe2x80x9cA Survey of Ultraviolet Absorbers in Commercially Available Sun Products,xe2x80x9d by Roelandts, et al., International Journal of Dermatology, Vol. 22, pages 247-55 (May 1985). Sunscreen compositions can also include a diester and/or polyester of a naphthalene dicarboxylic acid that photostabilizes sunscreen components.
Traditional sunscreen compositions for use on human skin are liquids, solids that require solvation, or particulate solids such as metal oxides. Incorporation of a sunscreen composition into a traditional cosmetic composition affects the physical characteristics of the cosmetic composition and creates obstacles to achieving desirable formulations. For example, incorporation of a liquid sunscreen composition, or a solid sunscreen composition in solution, lowers the viscosity and melting point of a cosmetic composition. As another example, metal oxide particulates, such as titanium dioxide, are difficult to maintain within a wax system due to their tendency to migrate out of the wax system.
Ultraviolet (UV) radiation absorbers also have been used in cosmetic compositions to protect the product from chemical or physical deterioration induced by ultraviolet light. UV absorbers, like sunscreen agents, have the ability to convert incident ultraviolet radiation into less damaging infrared radiation (heat). UV absorbers include allantoin PABA, butyl methoxydibenzoylmethane, ethyl diisopropylcinnamate, octyl methoxycinnamate, octyl salicylate, and PABA Various other UV absorbers can be found in the CTFA Cosmetic Ingredient Handbook, J. M. Nikitakis, Ed., 1st Edition (1988).
Accordingly, a continuing need exists for compounds useful in cosmetic compositions which provide desirable structure, viscosity, and tactile characteristics. It would also be desirable to have compounds useful in cosmetic compositions which are useful in the treatment of skin conditions such as adult acne, improving the firmness and smoothness of skin, and protecting skin from the damaging effects of ultraviolet radiation.
In brief, the invention generally is a class of salicylic acid esters and, more specifically, the invention is a class of diol-disalicylates useful as waxes, including cosmetic waxes, as ultraviolet radiation absorbers, and in the treatment of skin conditions including acne.
Accordingly, one aspect of the invention is a compound of formula (I) 
wherein n is an integer from 3 to 12, preferably an integer 4 to 12, more preferably an integer 4 to 8, most preferably 6.
Another aspect of the invention is a composition including a compound of formula (I) and a solvent including an ester of a C3-10 dibasic acid, preferably selected from the group consisting of diisopropyl sebacate, diisopropyl adipate, dioctyl maleate, dioctyl adipate, diethylhexyl naphthalate, and mixtures thereof.
Another aspect of the invention is a wax composition including a compound of formula (I) and a cosmetically useful material.
Yet another aspect of the invention is a cosmetic composition including a compound of formula (I) and a cosmetically useful material.
Still another aspect of the invention is a sunscreen composition including a compound of formula (1) and at least one of a sunscreen agent and an ultraviolet light absorber.
Another aspect of the invention is to provide a method of protecting skin from ultraviolet radiation including topically applying to the skin a compound of formula (I) in a cosmetically acceptable carrier, preferably with at least one of a sunscreen agent and an ultraviolet light absorber.
A further aspect of the invention is to provide a method of treating skin conditions selected from the group consisting of acne, psoriasis, seborrheic dermatitis, dandruff, warts, corns, calluses, ringworm infection, wrinkling, yellowing, leatheriness, mottling, and hyperpigmentation, the method including topically applying to the skin a safe and effective amount of a compound of formula (I), preferably in a cosmetically acceptable carrier, most preferably in a pharmaceutically acceptable carrier.
An additional aspect of the invention is to provide a method of increasing the sun protection factor of a sunscreen composition including adding a compound of formula (I) to the sunscreen.
Still another aspect of the invention is to provide a process for preparing a compound of formula (I), wherein n is an integer 3 to 12, including reacting salicylic acid with a C3-C12 diol.
Another aspect of the invention is to provide cosmetic compositions, including pressed face powder, loose face powder, pressed face foundation, blush, eyeshadow, anhydrous foundation, anhydrous mascara, anhydrous eyeshadow, glossy classic lipstick, matte classic lipstick, and volatile lipstick, that generally include about 0.01 wt. % to about 50 wt. % of a compound of formula (I).
Further aspects and advantages of the invention may become apparent to those skilled in the art from a review of the following detailed description, taken in conjunction with the appended claims. It should be noted, however, that while the invention is susceptible of embodiments in various forms, described hereinafter are specific embodiments of the invention with the understanding that the present disclosure is intended as illustrative, and is not intended to limit the invention to the specific embodiments described herein.